"Episode XXXVIII: The Birth of Evil, Part 2" (written as "The Birth of Evil" Part II on the episode's title card) is the thirty-eighth episode in the third season of Samurai Jack. This two part episode features Jack's father continuing his battle with Aku.
While Aku unleashes destruction upon the Emperor's kingdom as he watches helplessly trapped on a dark tree, Odin's white horse (named Sleipnir) arrives and frees him, taking the Emperor to a high mountain where he meets Ra, Vishnu, and Odin. The three gods explain what Aku is and take the pure spirit from him, which the gods, in the form of three monks, forge into an enchanted sword.
Armed with the sword and reinvigorated with silver shining armor, the Emperor, riding on a mystical cloud, charges back to battle Aku, who merely laughs, as no mortal weapon can harm him. The Emperor slashes at Aku with the enchanted sword, harming him and causing him confusion. The Emperor then explains where the sword came from, but Aku simply responds with blasts from his eye beams, forcing the Emperor to dodge the beams before slashing Aku's form again. Aku retaliates by turning into a flying dragon and chasing after him. After an intense chase, the Emperor slashes Aku's head off. This does not stop Aku, who morphs into a spider and manages to knock the emperor away. Then Aku explodes in a rain of black goo of his substance and takes the armor of fallen warriors and became a whole army, who then surround the Emperor.
After several suspenseful seconds of glaring at each other, the Aku-soldiers start laughing insanely, then suddenly stop before attacking the Emperor. Each one is cut down by the emperor until only one remains. As Aku flees in terror the emperor thrusts the sword into him and traps him in it, then shoves the sword in the ground as Aku is turned into a big craggy tree, vowing to return. The Emperor then goes back to his wife after hearing a baby cry and holds his newborn son. He then tells his wife they must have a plan in case Aku ever returns.
- Casting by
- Collette Sunderman
- The same voice clip of Aku screaming in pain from the sword is repeated twice more within the episode.
- This two-part episode takes place before the pilot episode, even though it aired two seasons later.